Printhead structure having fluid passages defined in silicon

ABSTRACT

A printhead structure is provided comprising a moulding, silicon wafer and a plurality of microelectromechanical ink ejection devices. The moulding at least defines a fluid reservoir and a first passage in fluid communication with the fluid reservoir. The silicon wafer at least defines a second passage spaced from the first passage and a third passage arranged to provide fluid communication between the first and second passages. The microelectromechanical ink ejection devices are in fluid communication with the second passage.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. application Ser. No.10/303,351 filed Nov. 23, 2002, now issued U.S. Pat. No. 6,871,937,which is a continuation of Ser. No. 09/608,779 filed on Jun. 30, 2000,now issued as U.S. Pat. No. 6,676,250, the entire contents of which areherein incorporated by reference.

FIELD OF THE INVENTION

This invention relates to a print engine. The invention has particularapplication in a print engine for use in an instantaneous print, digitalcamera. More particularly, the invention relates to an ink supplyassembly for supplying ink to a printhead of the print engine.

BACKGROUND TO THE INVENTION

It will be appreciated that a printhead of the printer engine of a pagewidth printer has a width dimension measured in fractions ofmillimeters. Typically the printhead has a width dimension of about sixhundred micrometers. In an array of ink jet nozzles, adjacent nozzlescould be spaced from each other by dimensions in the order of 100micrometers. While the substrate of the printhead is made from a siliconwafer a supply mechanism for supplying ink to the substrate is oftenmade out of plastic. To mold the plastic such that individual inksupplies are provided to each ink supply passage in the substrateresults in extremely fine tolerances with the consequential expense,which that entails.

By quote “page width” is meant that the printhead prints one line at atime on the print media without traversing the print media, orrastering, as the print media moves past the printhead.

SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided a printengine comprising:

a plurality of ink reservoirs;

a plurality of first passages each in fluid flow communication with arespective reservoir;

a plurality of second passages, each corresponding to a respective firstpassage, the second passages being spaced from the first passages;

a plurality of third passages, each connecting, in fluid flowcommunication, a respective first passage and the corresponding secondpassage; and

a plurality of microelectromechanical (MEMS) ink ejection devicesconnected in fluid flow communication with each second passage.

According to a further aspect of the invention there is provided anelongate printhead structure comprising:

a plurality of first parallel ink passages extending longitudinallyrelative to the printhead;

a plurality of second parallel ink passages, spaced from the firstpassages and extending longitudinally relative to the printhead, eachsecond passage corresponding to a respective one of said first passages;

a plurality of third passages each opening into a respective secondpassage, and connecting that passage in fluid flow communication withthe corresponding first passage, wherein each third passage extendssubstantially transversely relative to the printhead;

a plurality of fourth passages opening into each second passage, eachfourth passage extending substantially transversely relative to theprinthead; and

a plurality of individual microelectromechanical (MEMS) ink ejectiondevices, each device being connected with a respective fourth passage.

Preferably, each second passage is of smaller width than the respectivecorresponding first passage.

Preferably, the structure further comprises an ink distributor mouldingdefining a plurality of channels, each channel corresponding with, andopening into, a respective first passage. Each channel is preferablyconnected with an end of the respective first passage and is preferablyconnected in fluid flow communication with an ink supply reservoir.

The structure preferably further comprises a first silicon wafer whichdefines at least part of each second passage and each third passage. Thestructure also preferably further comprises a second silicon wafer whichis superposed on the first wafer and which defines said fourth passages.Preferably, the second silicon wafer defines part of each secondpassage. Each second passage preferably extends along, and opensthrough, a face of the first wafer, the second wafer being joined tosaid face.

Preferably, the structure further comprises a pair of elongate printheadcomponents, one of said components defining a plurality of longitudinalrecesses and the other of said components covering said recesses so thatthe recesses constitute said first passages. Said one componentpreferably defines at least a part of each third passage.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference tothe accompanying diagrammatic drawings in which:

FIG. 1 shows a three dimensional view of a print engine, includingcomponents in accordance with the invention;

FIG. 2 shows a three dimensional, exploded view of the print engine;

FIG. 3 shows a three dimensional view of the print engine with aremovable print cartridge used with the print engine removed;

FIG. 4 shows a three dimensional, rear view of the print engine with theprint cartridge shown in dotted lines;

FIG. 5 shows a three dimensional, sectional view of the print engine;

FIG. 6 shows a three dimensional, exploded view of a printheadsub-assembly of the print engine;

FIG. 7 shows a partly cutaway view of the printhead sub-assembly;

FIG. 8 shows a sectional end view of the printhead sub-assembly with acapping mechanism in a capping position;

FIG. 9 shows the printhead sub-assembly with the capping mechanism inits uncapped position;

FIG. 10 shows a schematic, three dimensional view of part of an inksupply arrangement, in accordance with the invention, for a printhead ofa print engine;

FIG. 11 shows a schematic, sectional end view of the ink supplyarrangement taking along line XI-XI in FIG. 10;

FIG. 12 shows a schematic, sectional end view of the ink supplyarrangement taken along line XII-XII in FIG. 10;

FIG. 13 shows a schematic, sectional end view of the ink supplyarrangement taken along line XIII-XIII in FIG. 10; and

FIG. 14 shows a schematic, sectional end view of the ink supplyarrangement taken along line XIV-XIV in FIG. 10.

DETAILED DESCRIPTION OF THE DRAWINGS

In the drawings, reference numeral 500 generally designates a printengine, in accordance with the invention. The print engine 500 includesa print engine assembly 502 on which a print roll cartridge 504 isremovably mountable.

The print cartridge 504 is described in greater detail in our co-pendingapplications entitled “A Print Cartridge” and “An Ink Cartridge” filedsimultaneously herewith as U.S. Ser. Nos. 09/607,993 and 09/607,251respectively, the contents of that disclosure being specificallyincorporated herein by reference.

The print engine assembly 502 comprises a first sub-assembly 506 and asecond, printhead sub-assembly 508.

The sub-assembly 506 includes a chassis 510. The chassis 510 comprises afirst molding 512 in which ink supply channels 514 are molded. The inksupply channels 514 supply inks from the print cartridge 504 to aprinthead 516 (FIGS. 5 to 7) of the printhead sub-assembly 508. Theprinthead 516 prints in four colors or three colors plus ink which isvisible in the infrared light spectrum only (hereinafter referred to as‘infrared ink’). Accordingly, four ink supply channels 514 are definedin the molding 512 together with an air supply channel 518. The airsupply channel 518 supplies air to the printhead 516 to inhibit thebuild up of foreign particles on a nozzle guard of the printhead 516.

The chassis 510 further includes a cover molding 520. The cover molding520 supports a pump 522 thereon. The pump 522 is a suction pump, whichdraws air through an air filter in the print cartridge 504 via an airinlet pin 524 and an air inlet opening 526. Air is expelled through anoutlet opening 528 into the air supply channel 518 of the chassis 510.

The chassis 510 further supports a first drive motor in the form of astepper motor 530. The stepper motor 530 drives the pump 522 via a firstgear train 532. The stepper motor 530 is also connected to a driveroller 534 (FIG. 5) of a roller assembly 536 of the print cartridge 504via a second gear train 538. The gear train 538 engages an engagableelement 540 (FIG. 2) carried at an end of the drive roller 534. Thestepper motor 530 thus controls the feed of print media 542 to theprinthead 516 of the sub-assembly 508 to enable an image to be printedon the print media 542 as it passes beneath the printhead 516. It alsoto be noted that, as the stepper motor 530 is only operated to advancethe print media 542, the pump 522 is only operational to blow air overthe printhead 516 when printing takes place on the print media 542.

The molding 512 of the chassis 510 also supports a plurality of inksupply conduits in the form of pins 544 which are in communication withthe ink supply channels 514. The ink supply pins 544 are receivedthrough an elastomeric collar assembly 546 of the print cartridge 504for drawing ink from ink chambers or reservoirs 548 (FIG. 5) in theprint cartridge 504 to be supplied to the printhead 516.

A second motor 550, which is a DC motor, is supported on the covermolding 520 of the chassis 510 via clips 552. The motor 550 is providedto drive a separating means in the form of a cutter arm assembly 554 topart a piece of the print media 542, after an image has been printedthereon, from a remainder of the print media. The motor 550 carries abeveled gear 556 on an output shaft thereof. The beveled gear 556 mesheswith a beveled gear 558 carried on a worm gear 560 of the cutterassembly 554. The worm gear 560 is rotatably supported via bearings 562in a chassis base plate 564 of the printhead sub-assembly 508.

The cutter assembly 554 includes a cutter wheel 566, which is supportedon a resiliently flexible arm 568 on a mounting block 570. The worm gear560 passes through the mounting block 570 such that, when the worm gear560 is rotated, the mounting block 570 and the cutter wheel 566 traversethe chassis base plate 564. The mounting block 570 bears against a lip572 of the base plate 564 to inhibit rotation of the mounting block 570relative to the worm gear 560. Further, to effect cutting of the printmedia 542, the cutter wheel 566 bears against an upper housing or capportion 574 of the printhead sub-assembly 508. This cap portion 574 is ametal portion. Hence, as the cutter wheel 566 traverses the cappedportion 574, a scissors-like cutting action is imparted to the printmedia to separate that part of the print media 542 on which the imagehas been printed.

The sub-assembly 506 includes an ejector mechanism 576. The ejectormechanism 576 is carried on the chassis 510 and has a collar 578 havingclips 580, which clip and affix the ejector mechanism 576 to the chassis510. The collar 578 supports an insert 582 of an elastomeric materialtherein. The elastomeric insert 582 defines a plurality of openings 584.The openings 584 close off inlet openings of the pins 544 to inhibit theingress of foreign particles into the pins 544 and, in so doing, intothe channels 514 and the printhead 516. In addition, the insert 584defines a land or platform 586 which closes off an inlet opening of theair inlet pin 524 for the same purposes.

A coil spring 588 is arranged between the chassis 510 and the collar 578to urge the collar 578 to a spaced position relative to the chassis 510when the cartridge 504 is removed from the print engine 500, as shown ingreater detail in FIG. 3 of the drawings. The ejector mechanism 576 isshown in its retracted position in FIG. 4 of the drawings.

The printhead sub-assembly 508 includes, as described above, the baseplate 564. A capping mechanism 590 is supported displaceably on the baseplate 564 to be displaceable towards and away from the printhead 516.The capping mechanism 590 includes an elongate rib 592 arranged on acarrier 593. The carrier is supported by a displacement mechanism 594,which displaces the rib 592 into abutment with the printhead 516 whenthe printhead 516 is inoperative. Conversely, when the printhead 516 isoperational, the displacement mechanism 594 is operable to retract therib 592 out of abutment with the printhead 516.

The printhead sub-assembly 508 includes a printhead support molding 596on which the printhead 516 is mounted. The molding 596, together with aninsert 599 arranged in the molding 596, define a passage 598 throughwhich the print media 542 passes when an image is to be printed thereon.A groove 700 is defined in the molding 596 through which the cappingmechanism 590 projects when the capping mechanism 590 is in its cappingposition.

An ink feed arrangement 702 is supported by the insert 599 beneath thecap portion 574. The ink feed arrangement 702 comprises a spine portion704 and a casing 706 mounted on the spine portion 704. The spine portion704 and the casing 706, between them, define ink feed galleries 708which are in communication with the ink supply channels 514 in thechassis 510 for feeding ink via passages 710 (FIG. 7) to the printhead516.

An air supply channel 711 (FIG. 8) is defined in the spine portion 704,alongside the printhead 516.

Electrical signals are provided to the printhead 516 via a TAB film 712which is held captive between the insert 599 and the ink feedarrangement 702.

The molding 596 includes an angled wing portion 714. A flexible printedcircuit board (PCB) 716 is supported on and secured to the wing portion714. The flex PCB 716 makes electrical contact with the TAB film 712 bybeing urged into engagement with the TAB film 712 via a rib 718 of theinsert 599. The flex PCB 716 supports busbars 720 thereon. The busbars720 provide power to the printhead 516 and to the other poweredcomponents of the print engine 500. Further, a camera print enginecontrol chip 721 is supported on the flex PCB 716 together with a QAchip (not shown) which authenticates that the cartridge 504 iscompatible and compliant with the print engine 500. For this purpose,the PCB 716 includes contacts 723 which engage contacts 725 in the printcartridge 504.

As illustrated more clearly in FIG. 7 of the drawings, the printheaditself includes a nozzle guard 722 arranged on a silicon wafer 724. Theink is supplied to a nozzle array (not shown) of the printhead 516 viaan ink supply member 726. The ink supply member 726 communicates withoutlets of the passages 710 of the ink feed arrangement 702 for feedingink to the array of nozzles of the printhead 516, on demand.

The arrangement of the printhead is shown in greater detail in FIGS. 10to 14 of the drawings. The ink supply member 726 is a block of siliconwafer which is mounted on the silicon wafer 724. The member 726 haschannels 728 formed therein. The channels 728 extend the length of themember 726.

As described above, the printhead 516 is a multi-color printhead havingnozzles 757 arranged in groups. Each group prints one color or theinfrared ink. The nozzles 757 are MEMS devices mounted on a surface 730of the silicon wafer 724 with the member 726 being mounted on an opposedsurface 732 of the silicon wafer 724. Hence, as shown more clearly inFIG. 10 of the drawings, each group of nozzles 757 is supplied by an inksupply passage 734.

Thus, each channel 728 of the member 726 communicates with itsassociated group of passages 734. Each channel 728 has a plurality ofink inlet openings 736, 738, 740 and 742. For example, the ink inletopenings 736 supply black ink to the first group of ink supply passages734 of the wafer 724. Instead, where three colors and infrared ink areprovided, the ink inlet openings 736 provide infrared ink to the firstgroup of passages. The inlet openings 738 provide magenta ink to thesecond group of nozzles via their inlet passages 734. The ink inletopenings 740 provide yellow ink to the third group of nozzles via theirpassages 734. The final group of inlet openings 742 provide cyan ink tothe fourth group of nozzles via their passages 734.

Each inlet opening 736, 738, 740, 742 is isolated from its neighboringopening via a transversely extending bead of sealing material 744. Itwill be appreciated that the ink feed arrangement 702 bears against thetop surface 746 of the member 726 further to isolate the openings 736 to742 from one another.

Also, it is to be noted that the TAB film 712 is bonded to the surface730 of the wafer 724 via beads of adhesive 748. The beads 748 furtherform a fluid tight seal against the side of the wafer 724.

Ink ejected from each MEMS device 757 is ejected through a passage 750in the nozzle guard 722. To maintain a surface 752 of the nozzle guardand a region 754 between the nozzle guard 722 and the wafer 724 free offoreign particles, air is blown on to the surface 752 of the nozzleguard 722 and, via inlet openings 756 from the channel 710 into theregion 754.

The member 726 is a silicon wafer and, accordingly, the channels 728 andthe inlet openings 736 to 742 are formed in the wafer by etchingtechniques.

As described in the introduction to the specification, the spacingbetween the passages 734 and the wafer 724 is of the order of onehundred micrometers. In contrast, each ink inlet opening 736 to 742 hasa length dimension L of approximately 0.5 millimeters. The spacingbetween adjacent inlet openings is also of the order of 0.5 millimeters.If one considers the width dimension of the printhead 516 as the Xdimension with a length of the printhead as a Y dimension the ink supplymember 726 effectively functions as an adapter converting a small Xdimension into a much larger Y dimension. Accordingly, it is easier tofabricate the feed passages of the ink feed arrangement 702, which is aplastic molding, than would be the case if the ink feed arrangement fedthe ink directly into the wafer 724 of the printhead 516.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

1. A printhead structure comprising: a casing mounted on a moulding todefine a fluid reservoir therebetween, the moulding comprising a recessand a first passage in fluid communication between the fluid reservoirand the recess; an elongate silicon wafer received in the recess of themoulding and at least defining at least a part of an elongate channeland a second passage, the elongate length of the channel extending theelongate length of the silicon wafer, the channel being spaced from thefirst passage and the second passage having an inlet side at the firstpassage and an outlet side at the channel arranged to distribute all inkat the inlet side to the outlet side between the first passage andchannel; a plurality of microelectromechanical ink ejection devices influid communication with the channel along the elongate length of thechannel; and a metal cap portion which encloses the casing and moulding.2. A printhead structure according to claim 1, wherein the channel is ofsmaller width than the first passage.
 3. A printhead structure accordingto claim 1, further comprising a second silicon wafer at least defininga third passage and a remaining part of the channel, the third passagebeing arranged to provide the fluid communication between the channeland the microelectromechanical ink ejection devices.
 4. A printheadstructure according to claim 3, wherein the channel extends along a faceof the first silicon wafer, the first and second silicon wafers beingjoined at said face.
 5. A printhead structure according to claim 1,wherein the moulding further defines a remaining part of the secondpassage.
 6. A printhead structure according to claim 5, wherein thesecond passage opens at a face of the silicon wafer, the silicon waferand the moulding being joined at said face.